I use a small electric fuel pump, rated at about 60l an hour for a bit under 1A. There are loads on eBay etc.
I run this pump on average about 1hr day, but use it more when the tank is stirred up when sailing or if there is a rolly anchorage.It picks up from the very bottom of the tank. I have only had it installed 6 months, but my fuel looks cleaner. I have not measured the flow, but estimate the output about 50l an hour after going through the filter.
I think its better to try and keep the polishing system separate from the main fuel system if possible, although you might consider a diversion system so you can run the main engine from the fuel polishing system in an emergency.
The same pump will work as a priming pump, or emergency lift pump if you want.
Well, it seems that racor fg 500 filters require 60 GPH flow to separate particulate and water properly.
I did some research on this when I installed my fuel polishing system. The consensus was that a slow flow rate provided as good if not better filtration and water separation than a high flow rate. There was some opinions that the “Turbo” spiral for water separation fuel may work better at a high rate, but this was discounted by those with specialist knowledge.